Cloud-seeding rules may help to determine the efficacy of the various delivery methods #CORiver

As part of the state-authorized weather modification plan, operators of cloud-seeding operations are required to complete annual “target versus control” analyses, comparing snowfall in target areas against similar non-targeted control areas. Over time, the data from those evaluations may help determine if cloud seeding really does boost snowfall by up to 15 percent, as claimed by the operators.

“This method is credible and develops relationships between snow data and tracks precipitation totals over time in both seeded areas and non-seeded areas to help track the efficacy of the program,” said Maria Pastore, of Glenwood Springs-based Grand River Consulting, who manages the central mountains cloud-seeding rogram.

“In addition, the State has new data types and evaluation methods suggested for cloud seeding programs,” Pastore said. “They are not required but are suggested as good periodic evaluations that can help the long-term sustainability of these programs.”

Cloud seeding in Colorado involves burning silver iodide in ground-based generators to inject tiny particles of the material into approaching weather systems. The silver iodide is said to provide nucleii for crystal formation and growth, helping to wring a bit of additional moisture from the clouds.

For the 2012-2013 season, the central mountains program will cost $293,600 and target an area of about 1,668 square miles of the Upper Colorado River Basin, generally above elevation 8,500 feet, in parts of Pitkin, Eagle, Summit, and Grand counties. If it works, the program could benefit A-Basin, Breckenridge, Keystone and Winter Park, all included in the target area.